[Bug fortran/103931] Type name "c_ptr" is ambiguous when iso_c_binding is imported both directly and indirectly

["aldot at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103931

--- Comment #18 from Bernhard Reutner-Fischer <aldot at gcc dot gnu.org> ---
(In reply to Bernhard Reutner-Fischer from comment #17)
> (In reply to Bernhard Reutner-Fischer from comment #16)
> 
> > I'm testing a more elaborate test which keeps check_for_ambiguous in the
> > same spot as before, but in that check, looks if the symtree (C_ptr in this
> > case, number 3) is listed in the generic interfaces after the existing check
> > that looks if the symbol itself is GENERIC.
> 
> This highlights cases like in use_24.f90 and use_27.f90 and requires
> follow-up changes that i'm not entirely comfortable with.

We can just mark the dt symbol (which is used to describe the generic
interface) as attr.generic = 1

This regtests cleanly and fixes the reported bug.


diff --git a/gcc/fortran/symbol.cc b/gcc/fortran/symbol.cc
index 221165d6dac..28ed1a32b9e 100644
--- a/gcc/fortran/symbol.cc
+++ b/gcc/fortran/symbol.cc
@@ -4977,6 +4986,10 @@ generate_isocbinding_symbol (const char *mod_name,
iso_c_binding_symbol s,
              if (!tmp_sym->attr.function
                  && !gfc_add_function (&tmp_sym->attr, tmp_sym->name, NULL))
                return NULL;
+
+             /* Mark the derived-type symbol in the generic interface
+                as generic.  */
+             dt_sym->attr.generic = 1;
            }

          /* Say what module this symbol belongs to.  */


i.e. it marks the dt as GENERIC, so the gmodule contents from comment #16
become
...
(('c_funptr' '__iso_c_binding' 2) ('c_ptr' '__iso_c_binding' 3)) // generic
interfaces
...
(2 'C_funptr' '__iso_c_binding' '' 1 ((DERIVED UNKNOWN-INTENT
UNKNOWN-PROC UNKNOWN UNKNOWN 0 0 GENERIC IS_BIND_C IS_C_INTEROP
PRIVATE_COMP) ((4 'c_address' (INTEGER 8 0 1 0 INTEGER ()) () () () (
UNKNOWN-FL UNKNOWN-INTENT UNKNOWN-PROC UNKNOWN UNKNOWN 0 0) PRIVATE ()))
PRIVATE (DERIVED 2 0 1 1 VOID ()) 0 0 () () 0 () () () 2 44 0)
3 'C_ptr' '__iso_c_binding' '' 1 ((DERIVED UNKNOWN-INTENT UNKNOWN-PROC
UNKNOWN UNKNOWN 0 0 GENERIC IS_BIND_C IS_C_INTEROP PRIVATE_COMP) ((5
'c_address' (INTEGER 8 0 1 0 INTEGER ()) () () () (UNKNOWN-FL
UNKNOWN-INTENT UNKNOWN-PROC UNKNOWN UNKNOWN 0 0) PRIVATE ())) PRIVATE (
DERIVED 3 0 1 1 VOID ()) 0 0 () () 0 () () () 2 42 0)